Facile preparation of attapulgite-based aerogels with excellent flame retardancy and better thermal insulation properties

A novel and environmentally friendly attapulgite-based aerogel with a three-dimensional fibrillary network structure was prepared by incorporation of nanometer-sized natural clay crystals, in this case attapulgite (ATP), into degradable poly(vinyl alcohol) (PVA), cotton cellulose nanowhisker, and melamine using only a simple blending method and subsequently a freeze-drying process. The ATP-based aerogel exhibits an abundant porosity with an average mesopore size of 8.0 nm in diameter. Compared to fragile and rigid inorganic aerogels, the as-prepared aerogel shows good flexibility and mechanical strength with a compressive strength of 9.65 × 10⁴ Pa and 10.19 × 10⁴ Pa at 20% and 40% of compressive strain, respectively. The limiting oxygen index (LOI) and vertical flame tests show that the resulting aerogel possesses excellent flame retardancy, with an LOI of 59.5%. Microcalorimetry test results show that the total heat release of the aerogel is as low as 5.1 KJ/g. Also, the sample shows a better thermal insulation property, with a thermal conductivity of about 0.045 W m⁻¹ K⁻¹ in air. Taking advantage of a simple and environmentally friendly fabrication, abundant natural clay resources, easy scalability, nearly no pollution emission in the process, and cost-efficient production, the ATP-based aerogel has great potential as ideal flame retardant and thermal insulation materials for many applications such as modern building construction or energy-efficient coatings. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47849.